Burned up hardware

I hooked up an old motherboard someone could not get working and got it working good for about a month (p4b533-v). I updated bios and then had a big problem, burned up hdd and two dvd drives. Put in a replacement hdd and worked good agian until I turned off the computer and turned it back on the following day. Another burned up hdd.
Checked bios hardware monitor and power supply is slightly high but acceptable at 12.15 volts. My biggest concern is could ASUS bios update be causing this? Or could the power supply be surging at restart?

 

all your ideas could be happening...i would guess it's more motherboard related, rather than power supply. The bios update would more likely be the culprit if you inadvertently used the wrong one.

 

12.15V is well within the ±10% tolerance level allowed so that's fine.

Assuming these are all EIDE devices attached to the same motherboard controller, then yes, I would be leaning towards a motherboard issue too. But I would not rule out the PSU until it is ruled out. Checking the voltage in the BIOS is not the best way because running the BIOS Setup Menu is just about the easiest task you can ask a computer to do. It is good to know the +12V is well within specs at idle, but what happens when you start putting demands on the CPU, RAM, graphics, and cooling? Does the computer work "perfectly" fine otherwise - that is, no freezes, reboots, jerky displays, odd errors? A "failing" PSU,

You need real time monitoring of your voltages to see if they are stable under full load too. But unfortunately, those programs don't measure for ripple or determine how "clean" the voltage is so you really need to get the PSU properly tested by a trained technician using an oscilloscope or power analyzer, or swap in a known good PSU.

I can see a BIOS update breaking the motherboard, even corrupting data on hard drive, but not "destroy" drives - especially the opticals.